<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <button>按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <button>按钮5</button>
    <script>
      //1.获取元素
      var btn = document.querySelectorAll('button');
      //.2事件类型

      //3.事件代码
      for (var i = 0; i < btn.length; i++) {
        btn[i].onclick = function () {
          for (var i = 0; i < btn.length; i++) {
            btn[i].style.backgroundColor = '';
          }
          this.style.backgroundColor = 'pink';
        };
      }
    </script>
  </body>
</html>
